/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.mail.util;

import jakarta.activation.DataHandler;
import jakarta.activation.DataSource;
import jakarta.mail.Message;
import jakarta.mail.MessagingException;
import jakarta.mail.Multipart;
import jakarta.mail.Part;
import jakarta.mail.internet.ContentType;
import jakarta.mail.internet.InternetAddress;
import jakarta.mail.internet.MimeBodyPart;
import jakarta.mail.internet.MimeMessage;
import jakarta.mail.internet.MimePart;
import jakarta.mail.internet.MimeUtility;
import jakarta.mail.internet.ParseException;
import jakarta.mail.util.ByteArrayDataSource;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Parses a MimeMessage and stores the individual parts such a plain text, HTML text and
 * attachments.
 *
 * @since 1.3
 */
public class MimeMessageParser {
  /** The MimeMessage to convert */
  private final MimeMessage mimeMessage;

  /** Plain mail content from MimeMessage */
  private String plainContent;

  /** Html mail content from MimeMessage */
  private String htmlContent;

  /** List of attachments of MimeMessage */
  private final List<DataSource> attachmentList;

  /** Attachments stored by their content-id */
  private final Map<String, DataSource> cidMap;

  /** Is this a Multipart email */
  private boolean isMultiPart;

  /**
   * Constructs an instance with the MimeMessage to be extracted.
   *
   * @param message the message to parse
   */
  public MimeMessageParser(final MimeMessage message) {
    attachmentList = new ArrayList<>();
    cidMap = new HashMap<>();
    this.mimeMessage = message;
    this.isMultiPart = false;
  }

  /**
   * Does the actual extraction.
   *
   * @return this instance
   * @throws Exception parsing the mime message failed
   */
  public MimeMessageParser parse() throws Exception {
    this.parse(null, mimeMessage);
    return this;
  }

  /**
   * @return the 'to' recipients of the message
   * @throws Exception determining the recipients failed
   */
  public List<jakarta.mail.Address> getTo() throws Exception {
    final jakarta.mail.Address[] recipients =
        this.mimeMessage.getRecipients(Message.RecipientType.TO);
    return recipients != null ? Arrays.asList(recipients) : new ArrayList<jakarta.mail.Address>();
  }

  /**
   * @return the 'cc' recipients of the message
   * @throws Exception determining the recipients failed
   */
  public List<jakarta.mail.Address> getCc() throws Exception {
    final jakarta.mail.Address[] recipients =
        this.mimeMessage.getRecipients(Message.RecipientType.CC);
    return recipients != null ? Arrays.asList(recipients) : new ArrayList<jakarta.mail.Address>();
  }

  /**
   * @return the 'bcc' recipients of the message
   * @throws Exception determining the recipients failed
   */
  public List<jakarta.mail.Address> getBcc() throws Exception {
    final jakarta.mail.Address[] recipients =
        this.mimeMessage.getRecipients(Message.RecipientType.BCC);
    return recipients != null ? Arrays.asList(recipients) : new ArrayList<jakarta.mail.Address>();
  }

  /**
   * @return the 'from' field of the message
   * @throws Exception parsing the mime message failed
   */
  public String getFrom() throws Exception {
    final jakarta.mail.Address[] addresses = this.mimeMessage.getFrom();
    if (addresses == null || addresses.length == 0) {
      return null;
    }
    return ((InternetAddress) addresses[0]).getAddress();
  }

  /**
   * @return the 'replyTo' address of the email
   * @throws Exception parsing the mime message failed
   */
  public String getReplyTo() throws Exception {
    final jakarta.mail.Address[] addresses = this.mimeMessage.getReplyTo();
    if (addresses == null || addresses.length == 0) {
      return null;
    }
    return ((InternetAddress) addresses[0]).getAddress();
  }

  /**
   * @return the mail subject
   * @throws Exception parsing the mime message failed
   */
  public String getSubject() throws Exception {
    return this.mimeMessage.getSubject();
  }

  /**
   * Extracts the content of a MimeMessage recursively.
   *
   * @param parent the parent multi-part
   * @param part the current MimePart
   * @throws MessagingException parsing the MimeMessage failed
   * @throws IOException parsing the MimeMessage failed
   */
  protected void parse(final Multipart parent, final MimePart part)
      throws MessagingException, IOException {
    if (isMimeType(part, "text/plain")
        && plainContent == null
        && !Part.ATTACHMENT.equalsIgnoreCase(part.getDisposition())) {
      plainContent = (String) part.getContent();
    } else {
      if (isMimeType(part, "text/html")
          && htmlContent == null
          && !Part.ATTACHMENT.equalsIgnoreCase(part.getDisposition())) {
        htmlContent = (String) part.getContent();
      } else {
        if (isMimeType(part, "multipart/*")) {
          this.isMultiPart = true;
          final Multipart mp = (Multipart) part.getContent();
          final int count = mp.getCount();

          // iterate over all MimeBodyPart

          for (int i = 0; i < count; i++) {
            parse(mp, (MimeBodyPart) mp.getBodyPart(i));
          }
        } else {
          final String cid = stripContentId(part.getContentID());
          final DataSource ds = createDataSource(parent, part);
          if (cid != null) {
            this.cidMap.put(cid, ds);
          }
          this.attachmentList.add(ds);
        }
      }
    }
  }

  /**
   * Strips the content id of any whitespace and angle brackets.
   *
   * @param contentId the string to strip
   * @return a stripped version of the content id
   */
  private String stripContentId(final String contentId) {
    if (contentId == null) {
      return null;
    }
    return contentId.trim().replaceAll("[\\<\\>]", "");
  }

  /**
   * Checks whether the MimePart contains an object of the given mime type.
   *
   * @param part the current MimePart
   * @param mimeType the mime type to check
   * @return {@code true} if the MimePart matches the given mime type, {@code false} otherwise
   * @throws MessagingException parsing the MimeMessage failed
   * @throws IOException parsing the MimeMessage failed
   */
  private boolean isMimeType(final MimePart part, final String mimeType)
      throws MessagingException, IOException {
    // Do not use part.isMimeType(String) as it is broken for MimeBodyPart
    // and does not really check the actual content type.

    try {
      final ContentType ct = new ContentType(part.getDataHandler().getContentType());
      return ct.match(mimeType);
    } catch (final ParseException ex) {
      return part.getContentType().equalsIgnoreCase(mimeType);
    }
  }

  /**
   * Parses the MimePart to create a DataSource.
   *
   * @param parent the parent multi-part
   * @param part the current part to be processed
   * @return the DataSource
   * @throws MessagingException creating the DataSource failed
   * @throws IOException creating the DataSource failed
   */
  protected DataSource createDataSource(final Multipart parent, final MimePart part)
      throws MessagingException, IOException {
    final DataHandler dataHandler = part.getDataHandler();
    final DataSource dataSource = dataHandler.getDataSource();
    final String contentType = getBaseMimeType(dataSource.getContentType());
    final byte[] content = this.getContent(dataSource.getInputStream());
    final ByteArrayDataSource result = new ByteArrayDataSource(content, contentType);
    final String dataSourceName = getDataSourceName(part, dataSource);

    result.setName(dataSourceName);
    return result;
  }

  /**
   * @return Returns the mimeMessage.
   */
  public MimeMessage getMimeMessage() {
    return mimeMessage;
  }

  /**
   * @return Returns the isMultiPart.
   */
  public boolean isMultipart() {
    return isMultiPart;
  }

  /**
   * @return Returns the plainContent if any
   */
  public String getPlainContent() {
    return plainContent;
  }

  /**
   * @return Returns the attachmentList.
   */
  public List<DataSource> getAttachmentList() {
    return attachmentList;
  }

  /**
   * Returns a collection of all content-ids in the parsed message.
   *
   * <p>The content-ids are stripped of any angle brackets, i.e. "part1" instead of "&lt;part1&gt;".
   *
   * @return the collection of content ids.
   * @since 1.3.4
   */
  public Collection<String> getContentIds() {
    return Collections.unmodifiableSet(cidMap.keySet());
  }

  /**
   * @return Returns the htmlContent if any
   */
  public String getHtmlContent() {
    return htmlContent;
  }

  /**
   * @return true if a plain content is available
   */
  public boolean hasPlainContent() {
    return this.plainContent != null;
  }

  /**
   * @return true if HTML content is available
   */
  public boolean hasHtmlContent() {
    return this.htmlContent != null;
  }

  /**
   * @return true if attachments are available
   */
  public boolean hasAttachments() {
    return !this.attachmentList.isEmpty();
  }

  /**
   * Find an attachment using its name.
   *
   * @param name the name of the attachment
   * @return the corresponding datasource or null if nothing was found
   */
  public DataSource findAttachmentByName(final String name) {
    DataSource dataSource;

    for (final DataSource element : getAttachmentList()) {
      dataSource = element;
      if (name.equalsIgnoreCase(dataSource.getName())) {
        return dataSource;
      }
    }

    return null;
  }

  /**
   * Find an attachment using its content-id.
   *
   * <p>The content-id must be stripped of any angle brackets, i.e. "part1" instead of
   * "&lt;part1&gt;".
   *
   * @param cid the content-id of the attachment
   * @return the corresponding datasource or null if nothing was found
   * @since 1.3.4
   */
  public DataSource findAttachmentByCid(final String cid) {
    final DataSource dataSource = cidMap.get(cid);
    return dataSource;
  }

  /**
   * Determines the name of the data source if it is not already set.
   *
   * @param part the mail part
   * @param dataSource the data source
   * @return the name of the data source or {@code null} if no name can be determined
   * @throws MessagingException accessing the part failed
   * @throws UnsupportedEncodingException decoding the text failed
   */
  protected String getDataSourceName(final Part part, final DataSource dataSource)
      throws MessagingException, UnsupportedEncodingException {
    String result = dataSource.getName();

    if (result == null || result.isEmpty()) {
      result = part.getFileName();
    }

    if (result != null && !result.isEmpty()) {
      result = MimeUtility.decodeText(result);
    } else {
      result = null;
    }

    return result;
  }

  /**
   * Read the content of the input stream.
   *
   * @param is the input stream to process
   * @return the content of the input stream
   * @throws IOException reading the input stream failed
   */
  private byte[] getContent(final InputStream is) throws IOException {
    int ch;
    byte[] result;

    final ByteArrayOutputStream os = new ByteArrayOutputStream();
    final BufferedInputStream isReader = new BufferedInputStream(is);
    final BufferedOutputStream osWriter = new BufferedOutputStream(os);

    while ((ch = isReader.read()) != -1) {
      osWriter.write(ch);
    }

    osWriter.flush();
    result = os.toByteArray();
    osWriter.close();

    return result;
  }

  /**
   * Parses the mimeType.
   *
   * @param fullMimeType the mime type from the mail api
   * @return the real mime type
   */
  private String getBaseMimeType(final String fullMimeType) {
    final int pos = fullMimeType.indexOf(';');
    if (pos >= 0) {
      return fullMimeType.substring(0, pos);
    }
    return fullMimeType;
  }
}
